In order to protect against failures in a computer network, network devices, such as routers or nodes, may establish backup tunnels over paths that offer an alternative to protected physical or logical network elements (e.g., communication links). It is often desirable, however, to take into account network constraints when establishing a backup tunnel. One such constraint is shared risk link groups (SRLGs), where a communication link and its associated SRLGs may be advertised to the network so that other nodes may utilize such advertisements when calculating paths in the network. For example, when different links share a common resource, such as an optical fiber or the like, they may participate in the same SRLG. Failure of the shared resource (the fiber in this example) may result in the failure of each of the communication links whose traffic is carried in the network using that shared resource.
A group of links or members may be organized and advertised to the network as a single connection or “bundle” for a variety of reasons including, for example, redundancy, load balancing, and/or increasing the available bandwidth between two nodes in the network. Each member of the bundle may be associated with one or more SRLGs, i.e., some SRLGs may belong exclusively to one member, or to a subset of the members in the bundle. These SRLGs may be further advertised to the network in the context of their constituent bundle member associations, e.g., the SRLGs may be advertised as a union of all members of the bundle. When establishing a path for a backup tunnel, a node, such as a point of local repair (PLR), may consider the SRLGs of the link it is trying to protect and, in fact, may calculate a path that is SRLG-diverse from the link being protected. That is, according to a prior implementation, an advertised bundle may be avoided when establishing a backup tunnel if the SRLG(s) associated with the communication link being protected is shared with any of the SRLGs for that bundle. However, such an implementation is inefficient and overly restrictive.